Pricing event covered hats but not taunts, and I'm stuck with them...

https://backpack.tf/item/4706960987

Sale 1) Sold for a Duped Sulphurous Officer's Ushanka (49.5 Keys) + 8 Keys + ~1 Key of Items

https://backpack.tf/profiles/76561198118685464#!/compare/1495756800/1495843200 - Buyer's Backpack

49.5 + 8 + 1 = 58.5, which rounds to 59 Keys

Ushanka Mini

https://backpack.tf/profiles/76561198075491803#!/compare/1495324800/1495411200 - Sold + ~4 Keys of Items for a Starstorm Slumber Coldsnap Cap (50 Keys)

https://backpack.tf/profiles/76561198122872975#!/compare/1495756800/1495843200 - Sold for a Smoking Mohawk (58.5 Keys)

http://imgur.com/a/5udly - 1 Month Unsold at 40 Keys

Taking 40 - 59 because both 46 and 59 took ~1 Day.

Sale 2) Sold for a Stare From Beyond Trencher's Topper (53.5 Keys) + 3 Keys

https://backpack.tf/profiles/76561198142320206#!/compare/1496534400/1496620800 - Buyer's Backpack

53.5 + 3 = 56.5, which rounds to 57 Keys

This was not directly used to price the Trencher (there was another sale at 60 Keys).